Since the 1980's, many organization are shifting from the analog telephony (also called PSTN—public switched telephone network) into newer Voice over IP telephony.
As VoIP telephony gained more popularity, production volumes increases and cost reduced. Competitive market conditions together with technological development assisted further VoIP cost reduction to a level that is similar or even lower than the older less capable PSTN telephony.
During the last decade, VoIP telephony became the industry standard for any small to large organization building a new system or retrofitting older PSTN system.
Among the reason that VoIP gained so much popularity over PSTN telephony are:                1. Better call quality.        2. Higher system reliability.        3. Long list of value added features such as: conference call, caller ID, phone directory, voice mail, email, call forwarding etc.        4. Low call cost (or even zero cost) on domestic and international calls.        5. Sharing the same physical infrastructure as computer network that already deployed.        For many organizations, the economical drive towards the transition from PSTN to VoIP telephony is strong, but still for many organizations there is an additional factor that delay or even stop this transition. This factor is security.        It is well accepted that VoIP telephony is having a long list of inherent security vulnerabilities compared to PSTN.        Few dominant security vulnerabilities are:                    1. Call being tapped and transmitted to a remote attacker;            2. Call information being transmitted to a remote attacker;            3. Phone handset or base microphone are activated by a remote attacker to enable audio eavesdropping at the vicinity of the phone;            4. Phone handset earphone element or base speaker are being exploited while user is unaware to enable audio eavesdropping at the vicinity of the phone;            5. Phone firmware stored on non-volatile memory or software running on volatile memory is being modified by a remote attacker in order to enable unsecure operations;            6. Phone having physical (for example implant) or software tampering due to supply-chain vulnerability.                        
Security efforts of the art concentrated on encrypting the voice data to prevent intercepting and decoding the call while the data is traveling in the Internet. Such encryption/decryption is standard, but requires low delay time. Example can be found by looking for:    Crypt secure messaging and VOIP service for Windows Phone.    www.gdmissionsystems.com/cyber/products/secure-voice/sectera-viper-phone
General information relating to security venerability, of computers, and more specifically to computer peripherals such as cameras and microphones may be found in the following patents and applications:
U.S. Pat. No. 8,988,532; to Aviv Soffer; titled “Secure video camera device”; discloses a secure video camera device for reducing the risk of visual and audio eavesdropping has a video camera and an electromechanical shutter behind a transparent cover in a secured enclosure. The shutter optically obscures the camera lens when the device is in secure state.
U.S. 20130219525; to Aviv Soffer; titled “Secure audio peripheral device”; discloses a secure audio peripheral device, coupled to a computer, capable of enabling a user to use audio devices such as a microphone, speakers or headset when the device is in operational state, while giving to the user a clear visual indication that the audio devices are enabled. The device simultaneously disables the microphone; and turns off the visual indication when the device is in secure state.
U.S. Pat. No. 7,808,974 B2 patent application; to Goangshivan Shawn Ying, Eugene L. Edmon, Carlton L. Brown titled: “Method and apparatus for Voice over Internet Protocol telephony using a virtual private network”; discloses an apparatus and methods for utilizing a Voice over Internet Protocol (VoIP) telephone with a built-in VPN client.
U.S. Pat. No. 8,195,958 B2 patent application; to Steffen Fries; titled: “Security module for encrypting a telephone conversation”; discloses VoIP module that encrypts/decrypts the voice channels between two subscribers to avoid eavesdropping. Disclosed security module may be used for encrypting a telephone conversation which enables encryption of the voice data in a heterogeneous network including a packet-oriented data network and a telephone network.
U.S. Pat. No. 8,789,141 B2 patent; to Jae-Sun Chin, Gregory Henderson, Michael Raftelis titled “Method and apparatus for providing security for an internet protocol service”; discloses communication networks and, more particularly, a method and apparatus for providing security for a Voice over Internet Protocol (VoIP) service provided over an Internet Protocol (IP) based network through discarding of signaling message by the endpoint device, when the signaling message is received from a device not associated with one of the group of internet protocol addresses in the access control list.
U.S. Pat. No. 5,832,075; to Gancarcik; titled “Off-hook detector for headset” discloses an event detector for a headset connected to a telephone, comprising a switch for short circuiting a microphone of the headset and a circuit for detecting a hookswitch flash in the event the duration of the short circuiting of the microphone is greater than a predetermined minimum and less than a predetermined maximum duration.